How to Select a data block's user in outliner?
Okay, after looking online and trying to acomplish the same thing with python, I found that it has not yet been implemented. This can be seen if you right click on "Actions" just above what you were clicking on, and click "Select" or "Select Linked", Blender tells you this has not been implemented. It appears the devs forgot to add this to sub-items.

Basically, the button's there but it can't be done yet.